昨天在自己電腦上連接mysql啟動web程序時，報出一些錯誤：
2018-09-17 16:30:28 ERROR DruidDataSource:646 : dataSource init error
com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:377)
at com.mysql.jdbc.Util.getInstance(Util.java:360)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:956)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:935)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:924)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:870)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2311)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2064)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:790)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:44)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:377)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:395)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:325)
at com.alibaba.druid.filter.FilterChainImpl.connection_connect(FilterChainImpl.java:148)
at com.alibaba.druid.filter.stat.StatFilter.connection_connect(StatFilter.java:211)
at com.alibaba.druid.filter.FilterChainImpl.connection_connect(FilterChainImpl.java:142)
at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1377)
at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1431)
at com.alibaba.druid.pool.DruidDataSource.init(DruidDataSource.java:618)
at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:915)
at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:911)
at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:98)
at org.apache.ibatis.mapping.VendorDatabaseIdProvider.getDatabaseProductName(VendorDatabaseIdProvider.java:82)
at org.apache.ibatis.mapping.VendorDatabaseIdProvider.getDatabaseName(VendorDatabaseIdProvider.java:66)
at org.apache.ibatis.mapping.VendorDatabaseIdProvider.getDatabaseId(VendorDatabaseIdProvider.java:53)
at org.mybatis.spring.SqlSessionFactoryBean.buildSqlSessionFactory(SqlSessionFactoryBean.java:445)
at org.mybatis.spring.SqlSessionFactoryBean.afterPropertiesSet(SqlSessionFactoryBean.java:336)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1637)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1574)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:545)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:351)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:108)
at org.springframework.beans.factory.support.ConstructorResolver.resolveConstructorArguments(ConstructorResolver.java:648)
at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:140)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1143)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1046)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:510)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202)
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.autowireResource(CommonAnnotationBeanPostProcessor.java:512)
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.getResource(CommonAnnotationBeanPostProcessor.java:486)
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor$ResourceElement.getResourceToInject(CommonAnnotationBeanPostProcessor.java:615)
at org.springframework.beans.factory.annotation.InjectionMetadata$InjectedElement.inject(InjectionMetadata.java:169)
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88)
at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessPropertyValues(CommonAnnotationBeanPostProcessor.java:308)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1214)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:543)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:772)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:839)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:538)
at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:444)
at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:326)
at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:107)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4812)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5255)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1408)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1398)
at java.util.concurrent.FutureTask.run(FutureTask.java:262)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NullPointerException
at com.mysql.jdbc.ConnectionImpl.getServerCharset(ConnectionImpl.java:2983)
at com.mysql.jdbc.MysqlIO.sendConnectionAttributes(MysqlIO.java:1873)
at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1802)
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1206)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2234)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2265)
... 72 more
（1）首先經過分析，以為是本機開啟了防火牆，檢查后，沒有開啟防火牆，並且通過navicat等工具可以連接，所以排除此原因；
（2）然后在網上搜索了一下，發現有網友遇到類似問題，代碼都沒有改動，之前連接測試數據庫和生產數據庫都沒有問題，但是連接本機新裝的mysql，
可能是本機mysql和測試環境的mysql版本不一致，經過查看，果然是這樣，我之前用的是5.1.43的jdbc連接jar包，但是本機裝的mysql是8.0.11，橫跨了好幾個大版本呢，修改后，再次重啟程序，但還是報錯！
（3）最后查看8.0.11的jar包里的driver.class有這么一句話，可能有的網友會直接報出這個提示：Loading class `com.mysql.jdbc.Driver'. This is deprecated. The new driver class is `com.mysql.cj.jdbc.Driver'，修改后，再次啟動，這次報錯新的錯了：關鍵字是The server time zone value
Caused by: com.mysql.cj.exceptions.InvalidConnectionAttributeException: The server time zone value '???ȲȺ????' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:59)
at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:83)
at com.mysql.cj.util.TimeUtil.getCanonicalTimezone(TimeUtil.java:128)
at com.mysql.cj.protocol.a.NativeProtocol.configureTimezone(NativeProtocol.java:2201)
at com.mysql.cj.protocol.a.NativeProtocol.initServerSession(NativeProtocol.java:2225)
at com.mysql.cj.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:1391)
at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:993)
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:852)
... 65 more
（4）參考了網友的提醒，在配置mysql的連接url時需要添加：&useSSL=false&serverTimezone=UTC，再次重啟程序，成功了！
希望能對遇到類似問題的園友有所幫助！
補充一點：mysql版本8，需要jdk8以上進行編譯！